This invention relates to automatic alignment of electronic displays, such as, for example, video touch screen displays that are used with electronic casino gaming equipment.
Video touch screens are commonly used in a wide variety of applications and have become increasingly popular for applications where faster, more intuitive user interfaces are desired and/or for applications that would otherwise require an impractically large number of panel-mounted push buttons or controls. For example, U.S. Pat. No. 5,951,397 to Dickenson discloses an electronic gaming machine having a touch screen overlay applied to an outer front surface of a cathode ray tube (CRT) or video display portion of the gaming machine. The gaming machine includes a row of push buttons mounted in a conventional manner on a ledge of the gaming machine so that the push buttons are physically convenient for a player seated on an elevated seat in front of the gaming machine.
The gaming device disclosed by Dickenson allows a player to select one from a plurality of available games such as, for example, blackjack, poker, keno, etc. and also allows the player to select either the conventional push-button controls or the touch screen to, provide inputs to and to control the operation of the game being executed by the gaming machine. However, with some games such as keno, for example, that require more inputs than can be practically provided with push buttons, the gaming machine may require the player to use the touch screen to provide inputs.
When the touch screen is used to provide inputs to the gaming device disclosed by Dickenson, one or more touch fields or soft switches are established within the area of the touch screen overlay. Each of these touch fields or soft switches may correspond to one or more actions or commands that may be performed by processing electronics within the gaming machine. Additionally, graphic indicia and textual information may be displayed on the CRT to indicate to the player the locations of the touch fields and what action or command will result from touching a particular touch field.
As is well known, one important aspect of using a touch screen overlay to provide inputs to a device having an electronic display is maintaining precise physical alignment or correspondence between the touch fields of the touch screen overlay and the displayed graphic indicia and/or text associated with each of the touch fields. For example, if the displayed graphic indicia or text drifts or moves with respect to the front surface of the display, the graphic indicia and/or text may no longer be aligned with or correspond to the desired respective touch fields within the touch screen overlay. Thus, the player of an electronic gaming device that uses a touch screen for inputs may touch the touch screen overlay in an area that appears to correspond to a particular graphic displayed on the front surface of the display to cause a desired action and the touch field associated with the touched location may instead carry out a different or unexpected action or possibly no action at all. As a result, the player, and casino patrons in general, may loose confidence in touch screen-based devices and may avoid playing games that require interaction via a touch screen.
Numerous attempts have been made to improve the alignment between the touch fields within a touch screen overlay and the displayed graphic indicia and/or text that corresponds to each of the touch fields. For example, U.S. Pat. No. 5,796,389 to Bertram et al. discloses a technique for calibrating the relationship between touch screen touch fields and the graphic indicia and/or text displayed on a CRT. As shown in FIG. 7, the technique taught by Bertram et al. displays a plurality of graphic calibration dots throughout the display area of the CRT and asks a user to touch the touch screen overlay at the location of each of these calibration dots. After all of the calibration dots have been touched, the technique taught by Bertram et al. solves a system of equations, which describes the relationships between the output signals generated by the touch screen electronics and the displayed calibration dots, to produce a pair of functions that maps touch screen locations to video display locations within the CRT.